1. Field of the Invention
The present invention relates generally to fluid transfer devices, and particularly to a rotary diaphragm pump having an elliptical band diaphragm driven by an articulating roller assembly.
2. Description of the Related Art
Fluid transfer devices, e.g., pumps, often use the principle of a distensible elastomeric diaphragm as the primary component therein. Various mechanisms are used to move the diaphragm and thereby change the volume of one or more chambers within the pump in order to move a fluid (air or liquid) through the pump. The diaphragm in such a pump generally has a flat, planar configuration when it is not distended by the drive mechanism. The diaphragm in such a pump configuration is secured about its periphery, and the drive mechanism generally is secured to the central area of the diaphragm. The stress imposed upon the diaphragm by being mechanically attached to other structure both about its periphery and its central area results in relatively large stress upon the diaphragm and correspondingly shortened life. Various hydraulically actuated diaphragm pumps have been developed in an effort to reduce the stress on the diaphragm, but such hydraulically actuated pumps generally suffer from reduced mechanical efficiency in comparison to mechanically actuated planar diaphragm pumps.
Another disadvantage of such conventional diaphragm pumps is that a single diaphragm generally corresponds to a single pump chamber. The efficiency and smoothness of operation of the pump is thus relatively limited in a manner somewhat analogous to a single cylinder reciprocating pump or engine, so that it has only one power stroke or pulse per revolution. In many applications, relatively smooth output of the pump, i.e., avoiding significant variations in output pressure during each revolution of the pump drive, is a very desirable feature. Conventional mechanically driven planar diaphragm pumps are incapable of providing such smooth fluid delivery unless equipped with additional components to smooth the pulses delivered from the pump.
Thus, a rotary diaphragm pump solving the aforementioned problems is desired.